1. Technical Field
The present invention relates to an electric field driving device, a liquid crystal device and an electronic apparatus.
2. Related Art
A liquid crystal device is one of electric field driving devices and modulates transmitted light by driving a liquid crystal using an electric field. One embodiment of the liquid crystal device is known as an FFS (Fringe Field Switching) mode liquid crystal device that drives a liquid crystal using a lateral electric field that is parallel to the substrates of the liquid crystal device. The liquid crystal device includes pixel electrodes and a common electrode. The pixel electrodes are provided on a face of one of the substrates, which faces the liquid crystal. The common electrode is laminated on the pixel electrodes via an insulating layer. Among these electrodes, the common electrode has a large number of slits formed therein. In the above described configuration, as a driving voltage is applied between the pixel electrodes and the common electrode, an electric field that has a line of electric force, extending from the upper face of the common electrode through the slits to the upper face of the pixel electrodes, is generated. At this time, liquid crystal molecules are driven by a component of the electric field, which is parallel to the substrates (lateral electric field) and generated above the common electrode, and thereby the alignment direction of the liquid crystal molecules are changed. In this manner, the FFS mode liquid crystal device drives the liquid crystal molecule and modulates incident light using the polarization conversion function.
FIG. 17A and FIG. 17B are enlarged plan views that focus on one of slits 27 formed in a common electrode 26 in an FFS mode liquid crystal device. FIG. 17A is a view that shows a state when no voltage is applied. A liquid crystal molecule 50a is aligned parallel to an X-axis, while the slit 27 extends in a direction (direction D) that is inclined to the X-axis. Here, when a driving voltage is applied, a lateral electric field is generated in a direction (direction C) perpendicular to the direction in which the slit 27 extends. As a result, the liquid crystal molecule 50a is rotated in a clockwise direction and then is aligned, for example, parallel to the lateral electric field, that is, along the direction C (see FIG. 17B).
At this time, a hue appears differently between when a display is viewed from a direction E parallel to the direction C and when a display is viewed from a direction F that is symmetrical to the direction E with respect to Y-axis because the apparent refractive index of the liquid crystal molecule 50a is different therebetween. For a similar reason, a hue appears differently between when a display is viewed from a direction G parallel to the direction D and when a display is viewed from a direction H that is symmetrical to the direction C with respect to Y-axis.
In order to improve such viewing angle dependency of a display color, a configuration has been proposed, as shown in FIG. 18, in which the extending direction in which the slits 27 are formed in the common electrode 26 is alternately changed for sub-pixels 4R, 4G, 4B corresponding to red, green and blue, which is described in JP-A-2000-29072.
However, in the above configuration, because the slits are bent at boundaries between the adjacent sub-pixels, there is a problem that a domain of the liquid crystal is likely to be produced owing to a disturbance of an electric field. In addition, when sub-pixels corresponding to even-numbered colors are arranged repeatedly in a line, there is a problem that the alignment direction of the liquid crystal matches between the sub-pixels corresponding to the same color and, as a result, viewing angle dependency of display color is not improved.